Apparatus for varying the wave form of alternating current



Dec. 27, 1927. 1,653,881

H. c. SNOOK APPARATUS FOR VARYING THE WAVE FORM OF ALTERNATING CURRENTFiled April 22, 1922 //7 vex? for:

Patented Dec. 2?, 1927.

UNITED STATES PATENT OFFICE.

HOMER C. SNOOK, 01 SOUTH ORANGE. NEW JERSEY, ASSIGNOR TO WESTERN ELEG-TRIO COMPANY, INCORPORATED, 0.1 NEW YORK, N. Y., A CORPORATION OI NEWYORK.

APPARATUS FOR VABYING THE WAVE FORM OF ALTERNATING CURRENT.

Application filed April 22, 1922. Serial No. 555,962.

This invention relates to a device for modifying the wave form of analternating cur rent and particularly to a device of this characteradapted for use in the exhaustion of vacuum tubes according to thecathode glow method disclosed in Patent No. 1,166,792, granted toapplicant January 4, 1916.

In the copending application of J. B.

Johnson, Serial No. 481,505, filed June 30, 1921, now U. S. Patent1,580,899, there is disclosed an apparatus for exhausting vacuum tubesin substantial accordance with the method disclosed in the above-notedpatent, wherein are provided means for causing the alternate bombardmentof the grid and plate electrodes and means for varying the energydelivered to the electrodes in the cathode glow according to theirrespective heat requirements.

It is an object of this invention to regu late the energy supplied toeither of the electrodes without a corresponding variation oi the energysupplied to the other electrode.

it. further object of the invention is a simple and eficient apparatusfor supplying energy to the electrodes and for varying the energydelivered to one electrode without varying the energy delivered to theother.

These objects are accomplished by providing two paths for supplyingelectrical energy to the electrodes so arranged that each path suppliescurrent flowing between the electrodes in a direction opposite to theflow in the other path, causing the electrodes to receive currentthrough said paths alternately and providing in each path means forvarying the voltage thereof and the cur rent flow therethrough.

The drawing'discloses one embodiment 01' the invention.

A vacuum tube 1 to be exhausted is connected by means of a tubing 2 to avacuum pump (not shown) and a valve 3 is provided in the tubing. Thegrid electrode 4. and the plate electrode 5 of the vacuum-tube 1 areelectrically connected to the terminals of the secondary winding 6 of atransformer having primary windings 7 and 8. Adjacent terminals of thewindings 7 and 8 are e1ectri- This arrangement provides two separateasymmetrical aths .for delivering energy from the transtormer to theelectrodes 4 and 5, or, in other words, a separate path for each halfwave of the alternating current due to the electromotive force inducedin the coil 14:- The electromotive force induced in coil 14 causes acurrent to flow in the right hand path. This current can flow only inone direction due to the rectifier 11 and therefore flows only duringone-half of the c cle. Similarly the current can flow in t e left handpath only in one direction which with respect to the coil 14 is oppositeto the direction of current in the right-hand path. Thus, the left-handcircuit provides a path for one half wave and the right-hand circuitprovides a path for the other half wave of the current due to theinduced electromotive force in the coil 14.

The flow of current through the windings 7 and 8 induces in the winding6 of the electrode circuit an alternating electromotive force which isthe resultant of the separate electromotive forces induced by thealternate flow of direct current in windings 7 and 8. This electromotiveforce, which may be of 300 to 1000 volts produces in the electrodecircuit an alternating current by means of which the electrodes 4 and 5are alternately subjected to the cathode low.

The exhaustion of t e tube is accomplished in evacuating the tube to avacuum of approximately one millimeter of mercury, after which an inertgas, such as ammonia, is introduced into the tube 1 and the valve 3closed. Alternating current is supplied to the primary 15, therebyinducing an alternating electromotive force in the secondary 14. Byvirture of the separate paths, a half waveof the induced currentalternately flows through the windin s 7 and 8. An alternatinelectromotive orce is induced in the win ing 6, which alternatelysupplies to the grid and plate the energ necessary for the cathode glow.The gri and plate are thereby alternately bombarded with electronssupplied by the ionization of the as in the tube. The nitrogen formed bythe ecomposition of the ammonia by the passage of the electron dischargebetween the grid and plate supplies electrons for the bombardment. Afterthe electrodes have been denuded of their occluded gas the other stepsof the method of applicants previously menticized patent are performedto evacuate the tu The energy supplied to the electrodes may be variedto heat the electrodes in accordance with their thermal capacity byregulating the amplitude of the currents flowing in the windings 7 and8. The amplitude of the current flowing through windings 7 may beregulated by varying the number of turns of the winding 14 included inthe left-hand circuit and by adjusting the resistance 12. Likewise theamplitude of the current flowing through thewinding 8 may be controlledby varying the number of turns of the winding 14 in the right-handcircuit and by adjusting the resistance 13. As the amplitude of thecurrent in either the left or right hand may be varied independently ofthe other, the energy supplied to one of the electrodes in the cathodeglow may be varied independently of the energy supplied to the otherelectrode.

The flow of current in the coil 7 will tend to induce in the coil 8 anelectromotive force in a direction opposite to the electromotive forceinduced in the portion of the coil 14 to the right of the point 17. Thealgebraic sum of these two elect-romotive forces is less than thepotential drop between the electrodes of the rectifier in the right-handcircuit and will not, therefore, be effective to cause a current flow inthe right-hand circuit through the rectifier. The flow of current in thecoil 8 will have a similar effect upon the lefthand circuit. Thus, theelectromotive force induced ineither the coil 7 or 8 by the flow ofcurrent through the other of said coils, will have no effect upon theelectromotive force induced in the electrode-circuit. The filament playsno part in the process of the invention.

It is, of course, understood that various modifications may be made inthis apparatus without in any way departing from the spirit of theinvention.

The invention claimed is:

1. In combination, a vacuum tube having two electrodes, a source ofcurrrent, connections between said source and said electrodes forming apath for delivering current in one direction between said electrodes,connections between said source and said electrodes forming a path fordelivering current in the opposite direction between said electrodes,and means in each path for determining the cur rent flow therethrough.

2. In combination, a source of alternating current, a vacuum tube havingtwo electrodes, a path between said sourceand said two electrodes forone half wave of alternating current, a second path between said sourceand said two electrodes for the other half wave of alternatin current,and means individual to'a each pet for modfying the form of the. halfwave flowing therethrough.

3. In combination, a vacuum tube having electrodes, a circuit connectionbetween two electrodes, two separate paths for electric currentinductively connected to said circuit,

means for passing current alternately through said paths to inducealternating current in the electrode circuit, and means for varying thecurrent flow in each of said paths.

4. The combination of a vacuum tube having electrodes, a circuitconnection between two electrodes, two circuits inductively connectedwith said electrode circuit, and means for passing current alternatelythrough said circuits to produce alternating current in the electrodecircuit.

5. The combination of vacuum tube having electrodes, means foralternately establishing a space discharge between said electrodes, inopposite directions and means for varying the energy delivered to eitherof said electrodes independently of the energy delivered to the other.

6. In combination, a vacuum tube having electrodes, an electrode circuitconnecting two of said electrodes, two circuits inductive- 13 connectedtherewith, means for supplying alternating current to each of saidcircuits, and means in each of said circuits for preventing the How ofone half wave of said current.

' 7. The combination of a vacuum tube having electrodes, an electrodecircuit connecting two of said electrodes, 9. pair of circuitsinductively connected therewith, a variable induction coil in eachcircuit, and a source of alternating current inductively connectedwitheach of said coils.

8. In combination, an electrical device, a pair of circuits inductivelyconnected therewith, 'a variable induction coil in each circuit, auni-directional current flow device in each circuit, and a source ofalternating current inductively connected with each of said coils.

9. In combination, an electrical device, a pair of circuits connectedtherewith, a variable induction coil in each circuit, a unidirectionalcurrent flow device in each cirwit, a variable resistance in eachcircuit, and a source of alternating current inductive- 1y connectedwith each of said coils.

10. The combination of an electrical device, a pair of circuitsinductively connected therewith, a rectifier common to said circuits, aninduction coil, part of which is a. por-

